Yeah, sorry, bad choice of words there. It is rich right through the range just reving it (not under load)

They warn against prelonged use, because of the heat range of the plug. I cant remeber off hand if it was hot or cold so I'll take your word on that one.

But apparently using it on a dyno is okay -just in case you have a dyno but no analytical gear to go with it

so potentially you could do a quick run around the block with the bonnet off and the little viewer scope pointed towards the driver .